JSON Schema : JSON Schema is a vocabulary that allows you to annotate and validate JSON documents.
Pro Git : The entire Pro Git book, written by Scott Chacon and published by Apress, is available here
DevDocs : DevDocs combines multiple API documentations in a fast, organized, and searchable interface.
Swagger : Swagger is a powerful open source framework backed by a large ecosystem of tools that helps you design, build, document, and consume your RESTful APIs...
This guide describes a set of HTTP+JSON API design practices, originally extracted from work on the Heroku Platform API.